1. Field of the Invention
The present invention relates to a driver and an image instrument which uses the driver, the driver driving a movable frame which is included a photographic lens and is driven for an image blur correction and focusing during imaging or which is included a camera and is a movable frame (moving frame, lens) holding a lens constituting the photographic lens.
2. Description of the Related Art
Recently, digital cameras which enable not only still image photography but also moving image photography have been on the market. When autofocus is performed in the photographic lens or a camera, a movable frame which holds some lenses that constitute the photographic lens or which holds an image pickup device is driven in the optical axis direction of the photographic lens. When a shake correction is made in the photographic lens or the camera, the frame which holds the lenses or the image pickup device is moved in a direction that intersects at right angles with the optical axis direction or inclined in the direction that intersects at right angles with the optical axis direction.
To move the movable frame which holds the photographic lens in the optical axis direction or in the direction that intersects at right angles with the optical axis direction in this way, independent drivers are needed to move the movable frame in each direction. Thus, in an image instrument such as a camera, the configuration is complicated and increased in size.
The movable frame which holds the photographic lens needs to be driven rapidly and precisely (with high positional precision) to accurately utilize a photographing opportunity. An electromagnetic motor such as a stepping motor or a voice coil motor is generally used to rapidly drive the movable frame.
However, the problem of these motors is that the motors oscillate and become uncontrollable in rapid driving at a predetermined velocity or more. Another problem of these motors is that if minute driving is attempted to drive the motors precisely (with high positional precision), driving with a predetermined drive amount or less for this minute driving is impossible.
Techniques associated with the above autofocus and shake correction are disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2010-170051, Jpn. Pat. Appln. KOKAI Publication No. 2005-351917, Jpn. Pat. Appln. KOKAI Publication No. 2006-209029, Jpn. Pat. Appln. KOKAI Publication No. 2012-232497, and Jpn. Pat. Appln. KOKAI Publication No. 2012-226205. Jpn. Pat. Appln. KOKAI Publication No. 2010-170051 discloses that a subject is imaged with what is known as wobbling in which a focus lens is vibrated in the optical axis direction, and a focal position is evaluated from an image by the imaging to drive the focus lens to the in-focus position. In the wobbling, a stepping motor is driven to wobble the focus lens.
Jpn. Pat. Appln. KOKAI Publication No. 2005-351917 discloses a driver which moves an image pickup device by a voice coil motor in a direction along a surface that intersects at right angles with the optical axis.
Jpn. Pat. Appln. KOKAI Publication No. 2006-209029 discloses driving a focus lens frame in the optical axis direction by a rectangular stack bimorph type piezoelectric element made of a ceramic material.
Jpn. Pat. Appln. KOKAI Publication No. 2012-232497 discloses a piezoelectric stack film made of a polylactic acid.
Jpn. Pat. Appln. KOKAI Publication No. 2012-226205 discloses a driver which uses a voice coil motor for driving an image pickup device in two directions (X-direction and Y-direction) that intersect at right angles with each other in a plane that intersects at right angles with the optical axis of a photographic lens and driving an image pickup device in a rotation direction around the optical axis. The driver further drives the image pickup device in the optical axis direction by a piezoelectric body.